1. Field of the Invention
The present invention relates to transmission method and radio apparatus utilizing said method, and it particularly relates to a transmission method in which a control is performed so that the transmitted signals are received with nearly constant power, and a radio apparatus utilizing said method.
2. Description of the Related Art
The adaptive array antenna changes successively the directivity of antenna in accordance with the position of an apparatus, which is targeted party to the communication, and the propagation environment so as to improve the communication quality and increase the number of users that can be handled. When the transmission power control is applied to the adaptive array antenna, the increased error in the control may result from the fluctuation of directional gain, which cannot be controlled by merely raising or reducing the transmission power. That is, although the targeted communication apparatus can receive signals with the sufficiently large power if the directional gain is large, there is a possibility that interference is caused in other communication apparatuses. On the other hand, if the directional gain is small, the targeted communication apparatus cannot receive the sufficient power, so that the communication quality deteriorates.
According to the conventional transmission power control technology applied to the adaptive array antennas, the directional gain is calculated from the received weight and the transmission array response vector, which is information on the position of antenna normalized by the transmission carrier frequency. Then, the correction value of amplitude in the transmission weight is computed so that the directional gain becomes a desired value. And when transmitting signals, the transmission power control is carried out using the correction value of amplitude in the transmission weight (for example, see Reference (1) in the following Related Art List).